Melibe engeli
Risbec, 1937

Order: NUDIBRANCHIA
Suborder: DENDRONOTINA
Family: Tethydidae

DISTRIBUTION

Reported from New Caledonia but probably has a much wider distribution.

PHOTO

Koumac Beach (=Baie de Ouanap), near Koumac, New Caledonia, 20°34'S, 164°16'E, Mixed soft and hard substrate, grassbeds, algae, 22 October 1993, many, 43-54mm long alive. UPPER: lateral view of animal crawling down sea grass blade. Note egg mass at top. LOWER LEFT: upper view of oral hood showing greatly elaborated right rhinophore stalk and small rhinophore club (arrowed). LOWER RIGHT: 'shrimp's eye' view of oral hood about to drop down and capture its prey. Note double row of sensory papillae around edge of hood. The 'mouth' is arrowed. PHOTOS: Bill Rudman.

This can be identified with M. engeli, which has not been re-examined since Risbec's accounts. The transparent body, almost cylindrical cerata, abruptly truncated at the tip fits Risbec's description. This species is small, 50mm in Risbec's account, but both Risbec's and my observations of egg-laying show that it is not a juvenile of one of the larger species of the genus. The blunt ceratal tip is usually decorated with four or five long tapering papillae and there is a rounded flat blade on the posterior side of the rhinophore sheath, papillate along its edge. Brown zooxanthellae are scattered throughout the body. It can swim by lateral flexion of the body, and readily fed on small crustacea, both crabs and shrimps, when they were put into the aquaria. This species has only been recorded from New Caledonia.

Species of Melibe feed on shrimps, crabs and other small crustacea which they catch by waving the inflated oral hood over the substrate like a metal detector. When the sensory papillae touch a crustacean the hood rapidly closes, trapping the prey inside where it is gradually manipulayed back to the 'mouth'. Species of Melibe lack a radula, prey remaining alive in the gut until killed by digestive juices.

Reference:
• Risbec, J. (1937). Note préliminaire au sujet de nudibranches Néo-Calédoniens. Bulletin Muséum National d'Histoire Naturelle Paris, series 2,9: 159-164.

Authorship details
Rudman, W.B., 2000 (March 2) Melibe engeli Risbec, 1937. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/melienge

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